1. Field of the Invention
This invention relates to a method and apparatus for sensing the condition of a gas, and more specifically, to a method and apparatus particularly suitable for analyzing dirty gas and/or gas containing an explosive mixture. As used in this specification, the term "condition" or "condition of a gas" is intended to refer to either the physical or chemical or other properties of the gas being analyzed.
2. Description of the Prior Art
Gas analyzers that utilize a convection loop or bring a portion of the sample up past a gas sensing element and back into the main sample flow stream are used for the analysis of gaseous combustion products from combustion processes, particularly those involving suspended solids in the gas products. However, such analyzers suffer from two distinct disadvantages:
A. When the sample contains a high concentration of low-density solids, these may be carried upwards into the heated section of the flow loop where they become concentrated because of reduced velocity due to changes in the flow path diameter and/or the lower density and viscosity of the gas at the location and, thus, cause plugging of the systems; and
B. IF THE SAMPLE CONTAINS AN EXPLOSIVE MIXTURE OF GAS CONSISTING OF SUFFICIENT OXYGEN AND FUEL GAS TO IGNITE, THIS SAMPLE WILL BE IGNITED IN THE HEATED SECTIONS OF THE FLOW PATH AND THE RESULTING EXPLOSION CAN PROPAGATE THROUGH THE SAMPLE FLOW PATH TO THE CHAMBER FROM WHICH IT ORIGINATED.
Accordingly, there is a need for a method and apparatus particularly adapted for analyzing dirty gas and/or gas containing an explosive mixture without encountering the risk of plugging the analyzer system or precipitating an unwanted explosion.